It's streamlined and pretty behind our standard rear light mount. With an acceleration sensor inside, it lights up as soon as you start slowing down - even before the built in brake lights, if you have any.
It's also a good redundant rear light (independent from on-board battery), as good as the Superflash. I always recommend one steady light (easier to judge distance) and a second, independent strobe light to catch attention from afar.
Cost is 60 € plus shipping.
The light mount in aluminium with first class stainless steel bolt screws on the top blind rivet of the WAW tail. For the Quest in the pictures we drilled a new hole.